1. Field of the Invention
The present invention is generally concerned with clutch release bearings intended primarily, but not exclusively, for controlling the clutch mechanism of an automotive vehicle.
2. Description of the Prior Art
As is known, a clutch release bearing generally comprises an operating member, adapted to be acted on by a control member, in practice a clutch release yoke, and a driving member linked axially to the operating member and adapted, when acted on by the latter, to operate the clutch release mechanism of the clutch.
The present invention is more particularly directed towards the case where the operating member comprises a transverse flange, hereinafter refered to for convenience as the bearing flange, on which the control member acts and on the surface of which is disposed a wear-resistant plate, appropriately fastened to it in the axial direction.
This is the case, in particular, when the operating member is made from a synthetic material, the wear-resistant plate then associated with its bearing flange being intended to prevent direct action of the control member on it, which could lead to rapid deterioration through wear, the plate being adapted to provide of itself sufficient resistance to wear with regard to such action.
A clutch release bearing in which the bearing flange of a synthetic material operating member is equipped in this way with a surface-mounted wear-resistant plate is described in French Patent of Addition No. 2 151 146 filed Aug. 20, 1971 under application No. 71 30367.
This French Patent of Addition proposes to provide the axial attachment of the wear-resistant plate to the operating member bearing flange by means of attachment lugs in the form of pegs or strips projecting from the bearing flange and having a root portion integral therewith, each peg or strip having a retaining shoulder facing the bearing flange for retaining the wear-resistant plate.
These attachment lugs offer the advantage of permitting the wear-resistant plate to be fitted to the operating member with a simple snap-fastener action, the wear-resistant plate causing temporary elastic deformation of the attachment lugs when axially engaged therewith, the attachement lugs subsequently returning to their initial configuration to provide an axial retention function by virtue of their retaining shoulder.
Although the practical embodiments of the attachment lugs proposed in the aforementioned French Patent of Addition constitute a satisfactory approach, they have the following disadvantages.
First of all, being in practice on the surface of the bearing flange from which they project, these attachment lugs necessarily have a length between their root portion and retaining shoulder which is too short for the necessary bending effect during snap-action engagement of the wear-resistant plate, as this length is strictly limited to the corresponding thickness of the wear-resistant plate.
Also, in the practical embodiments described in the aforementioned French Patent of Addition, there is no provision for indexing of the wear-resistant plate relative to the operating member during snap-action engagement of the wear-resistant plate on the bearing flange of the latter, the wear-resistant plate becoming engaged on an axial centering surface on the operating member only when such snap-action engagement is completed. Thus if the wear-resistant plate is not presented correctly relative to the corresponding snap-fastener attachment lugs during its axial engagement therewith, the wear-resistant plate can cause unwanted deformation of these attachment lugs, of a kind to compromise their proper working conditions and longevity. Nor is correct presentation of the wear-resistant plate relative to the centering surface on which it must be engaged necessarily obtained.
Finally, in these practical embodiments, these attachment lugs in fact have a two-fold function: on the one hand, as previously mentioned, they link the wear-resistant plate to the associated bearing flange in the axial direction and, on the other hand, they prevent the wear-resistant plate rotating relative to the bearing flange.
They may therefore be subjected to shear loads and, since they are designed to be capable of elastic deformation, do not necessarily have the appropriate characteristics to enable them to withstand such shear loads.
A general objective of the present invention is to provide an arrangement which overcomes these disadvantages.